Surface profile for semiconductor region

ABSTRACT

One or more techniques or systems for controlling a profile of a surface of a semiconductor region are provided herein. In some embodiments, an etching to deposition (E/D) ratio is set to be less than one to form the region within the semiconductor. For example, when the E/D ratio is less than one, an etching rate is less than a deposition rate of the E/D ratio, thus ‘growing’ the region. In some embodiments, the E/D ratio is subsequently set to be greater than one. For example, when the E/D ratio is greater than one, the etching rate is greater than the deposition rate of the E/D ratio, thus ‘etching’ the region. In this manner, a smooth surface profile is provided for the region, at least because setting the E/D ratio to be greater than one enables etch back of at least a portion of the grown region.

RELATED APPLICATION

This application is a divisional of U.S. Non-Provisional patentapplication Ser. No. 13/665,159, titled “SURFACE PROFILE FORSEMICONDUCTOR REGION” and filed on Oct. 31, 2012, which is incorporatedherein by reference.

BACKGROUND

Generally, a region of a semiconductor, such as a region formed based onepitaxial growth or chemical vapor deposition (CVD), is associated witha surface profile that is rough. For example, such roughness isassociated with RC tailing, undulation, or looser contact landings.

SUMMARY

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to be an extensive overview ofthe claimed subject matter, identify key factors or essential featuresof the claimed subject matter, nor is it intended to be used to limitthe scope of the claimed subject matter.

One or more techniques or systems for controlling a surface profile fora region of a semiconductor are provided herein. Generally, a region isformed based on at least one of epitaxial growth or chemical vapordeposition (CVD). During formation, the region is associated with anetching to deposition (E/D) ratio. For example, the E/D ratio is set toa first number less than one during formation, at least because anetching rate of the E/D ratio is less than a deposition rate of the E/Dratio. In this way, the region is formed, at least because the E/D ratioprovides for a net deposition, for example. In some embodiments, theregion comprises a surface associated with a surface profile. Forexample, the surface profile of the surface of the region is rough atleast due to a nature of formation of the region. In some embodiments,the E/D ratio is set to a second number greater than one to etch back atleast a portion of the region, such as when formation is at a desiredthickness. In this way, the surface profile of the surface of the regionis controlled to smooth the surface of the region by etching back atleast the portion of the region. Accordingly, the surface profile forthe region of the semiconductor is smoothed.

The following description and annexed drawings set forth certainillustrative aspects and implementations. These are indicative of but afew of the various ways in which one or more aspects are employed. Otheraspects, advantages, or novel features of the disclosure will becomeapparent from the following detailed description when considered inconjunction with the annexed drawings.

DESCRIPTION OF THE DRAWINGS

Aspects of the disclosure are understood from the following detaileddescription when read with the accompanying drawings. It will beappreciated that elements, structures, etc. of the drawings are notnecessarily drawn to scale. Accordingly, the dimensions of the same maybe arbitrarily increased or reduced for clarity of discussion, forexample.

FIG. 1 is a cross-sectional view of an example region of a semiconductorassociated with a controlled surface profile during formation, accordingto some embodiments.

FIG. 2 is a top-down or layout view of an example region of asemiconductor associated with a controlled surface profile duringformation, according to some embodiments.

FIG. 3 is an example region of a semiconductor associated with acontrolled surface profile and an associated doping concentration graph,according to some embodiments.

FIG. 4 is a flow diagram of an example method for controlling a surfaceprofile for a region of a semiconductor, according to some embodiments.

FIG. 5 is a flow diagram of an example method for controlling a surfaceprofile for a region of a semiconductor, according to some embodiments.

DETAILED DESCRIPTION

Embodiments or examples, illustrated in the drawings are disclosed belowusing specific language. It will nevertheless be understood that theembodiments or examples are not intended to be limiting. Any alterationsand modifications in the disclosed embodiments, and any furtherapplications of the principles disclosed in this document arecontemplated as would normally occur to one of ordinary skill in thepertinent art.

It will be appreciated that ‘layer’, as used herein, contemplates aregion, and does not necessarily comprise a uniform thickness. Forexample, a layer is a region, such as an area comprising arbitraryboundaries. For another example, a layer is a region comprising at leastsome variation in thickness.

It will be appreciated that a region is generally formed based on atleast one of epitaxial growth or chemical vapor deposition (CVD). Insome examples, formation of the region is associated with an etching todeposition (E/D) ratio. For example, when the E/D ratio is less thanone, a deposition rate of the E/D ratio is greater than an etching rateof the E/D ratio. Accordingly, when the E/D ratio is less than one, theregion is associated with a net deposition, as a whole. For example, ifthe etching rate is one nanometer per minute and the deposition rate isfour nanometers per minute, the E/D ratio is 0.25 and three nanometersare deposited on the region per minute. Conversely, when the E/D ratiois greater than one, a deposition rate of the E/D ratio is less than anetching rate of the E/D ratio. Accordingly, when the E/D ratio isgreater than one, the region is associated with a net etch, as a whole.For another example, if the etching rate is four nanometers per minuteand the deposition rate is one nanometer per minute, the E/D ratio isfour and three nanometers are etched from the region per minute.

FIG. 1 is a cross-sectional view 100 of an example region of asemiconductor associated with a controlled surface profile duringformation, according to some embodiments. In some embodiments, a region102 is formed during a first time, a second time, or a third time. Forexample, 100A and 100B are associated with formation of the region 102at the first time. Additionally, 100C and 100D are associated withformation of the region 102 at the second time and third time,respectively. In some embodiments, the second time is after the firsttime and the third time is after the second time. At 100A, region 102Ais formed based on at least one of epitaxial growth, chemical vapordeposition (CVD), etc. In some embodiments, region 102A comprises asurface 104A. According to some examples, 104A is associated with asurface profile that is rough. In some embodiments, region 102A isassociated with a thickness 110A. Additionally, an E/D ratio associatedwith region 102A of 100A at the first time is less than one, accordingto some embodiments, at least because the region 102A is being formed.In some embodiments, the E/D ratio is set to a first number less thanone during at least one of formation of the region 102 or the firsttime. At 100B, region 102B is formed and comprises surface 104B.Similarly, 104B is associated with a rough surface profile.Additionally, region 102B is associated with a thickness 110B greaterthan 110A. In some embodiments, the E/D ratio associated with region102B of 100B is the same as the E/D ratio associated with region 102A of100A. In some embodiments, the E/D ratio associated with 100B is lessthan one. In some embodiments, the second time is determined based on athickness of a region. For example, the second time is determined whenthickness 110B of region 102B is greater than a desired thickness, suchas ten nanometers, for example. It will be appreciated that while theE/D ratio is less than one, the thickness of the region, such as 110B ofregion 102B, will grow as time passes. At 100C, region 102C is formed oretched back at a second time, according to some embodiments. Forexample, region 102C comprises surface 104C. According to some aspects,104C is associated with a surface profile that is smoother than thesurface profile of 104B, for example. In some embodiments, region 102Cis associated with a thickness 110C. For example, thickness 110C is lessthan thickness 110B of 100B, at least because the E/D ratio of 100C isadjusted accordingly. For example, the E/D ratio associated with 100C isset to be a second number greater than one at the second time, at leastbecause when the E/D ratio is greater than one, 104C is etched back ortrimmed, thereby smoothing or trimming surface 104C. At 100D, region 102is formed according to some embodiments, at least because surface 104Cis at least one of trimmed, etched back, smoothed, or removed. Accordingto some aspects, region 102 is associated with a surface profile that issmoother than the surface profile of 104C, for example. In someembodiments, region 102 is associated with a thickness 110 less thanthickness 110C of 100C. In some embodiments, the E/D ratio associatedwith 100D is returned to the first number less than one, such as at thethird time. Accordingly, region 102 of 100D continues growth after etchback of surface 104C, for example. In this way, the surface profile forregion 102 is controlled or smoothed, and associated surface roughnessor undulation is mitigated. In this way, a smoother or flat surface forregion 102 is provided. Additionally, it will be appreciated that theetch back enables improved contact landing and RC distribution, thusmitigating RC tailing or noise associated with a semiconductorcomprising region 102, for example.

Additionally, in some embodiments, a first material is applied to theregion 102 as a boost for a device or a semiconductor comprising theregion 102. For example, Germanium (Ge) is applied to the region 102 toboost the device. In some embodiments, the application of Ge induces oris associated with compressive stress, thus enhancing at least one ofelectron mobility or hole mobility for the region 102. In someembodiments, the smoothing associated with the etch back of region 102mitigates stress relaxation associated with a rough surface profile,thus enhancing at least one of electron mobility or hole mobility forthe region 102. In some embodiments, a concentration of the firstmaterial, such as a Ge concentration, is adjusted based on the E/Dratio. For example, when the E/D ratio is set to the first number at afirst time, the first material is applied at a first concentration.Additionally, when the E/D ratio is set to the second number at a secondtime, the first material is applied at the second concentration, wherethe second concentration is different than the first concentration, atleast because a change in the E/D ratio affects a distribution of thefirst material, for example. In some embodiments, when the E/D ratio isset to the first number at a third time, the first material is appliedat the first concentration. In some embodiments, the secondconcentration is determined based on at least one of the first number,the second number, a difference between the first number and the secondnumber, a rate of change between the first number and the second number,etc. In some embodiments, at least one of the first number or the firstconcentration is a baseline, for example. In some embodiments, a surfaceroughness is associated with at least one of surface 104A, surface 104B,surface 104C, or region 102. In some embodiments, the surface roughnessassociated with region 102 is from at least about five nanometers ingrain size to at least about forty nanometers in grain size. However, itwill be appreciated that in other embodiments, the surface roughness isat least one of greater than forty nanometers in grain size or less thanfive nanometers in grain size.

FIG. 2 is a top-down or layout view 200 of an example region of asemiconductor associated with a controlled surface profile duringformation, according to some embodiments. It will be appreciated thatFIG. 2 is similar to FIG. 1, except that 100A, 100B, 100C, and 100D areassociated with top-down views of regions in FIG. 2, rather than thecross-sectional views of FIG. 1. For example, 100A is associated with afirst time. Additionally, a surface 104A of region 102 is grown, atleast because the E/D ratio associated with 100A is set to a firstnumber less than one. Similarly, 100B is associated with surface 104B ofregion 102, where the E/D ratio is less than one. In some embodiments,100B is associated with the first time. In some embodiments, at leastone of surface 104A or 104B is associated with a rough surface profile.In some embodiments 100C is associated with a second time after thefirst time. At 100C, at least a portion of surface 104C of region 102 isetched back, at least because the E/D ratio associated with 100C isadjusted to be greater than one. For example, the E/D ratio is adjustedto be greater than one at a third time. In some embodiments, the E/Dratio is set to be less than one based on a thickness of region 102,such as 110 of 100D of FIG. 1, for example. It will be appreciated thata surface profile of surface 104C is smoother than the surface profilesof surfaces 104A and 104B, at least because the E/D ratio of 100C is setto a second number greater than one, enabling at least some of thesurface 104C to be etched back or smoothed. At 100D, the surface 104C ofregion 102 is removed to expose region 102. In some embodiments, 100D isassociated with a third time. It will be appreciated that a surfaceprofile of region 102 is smoother than the surface profiles of surfaces104A,104B, or 104C, at least because the rough surface profiles ofsurfaces 104A,104B, or 104C are at least one of etched back, removed, orsmoothed. In some embodiments, the E/D ratio is returned to the firstnumber less than one at the third time.

FIG. 3 is an example region 102 of a semiconductor associated with acontrolled surface profile and an associated doping concentration graph310, according to some embodiments. For example, the region 102 of FIG.3 comprises a first sub-region 302A, a second sub-region 302B, and athird sub-region 302C. Additionally, the region 102 is associated with athickness 110. In some embodiments, the region 102 of FIG. 3 is the sameregion as region 102 of 100D of FIG. 1. In some embodiments, the regionis formed based on epitaxial growth or chemical vapor deposition (CVD).Accordingly, an etching to deposition (E/D) ratio is associated with theformation of region 102. For example, at a first time, when the thirdsub-region 302C is being formed, the E/D ratio is set to a first number,such as a number less than one. In some embodiments, when the E/D ratiois less than one, a deposition rate of the E/D ratio is greater than anetching rate for the E/D ratio. Accordingly, a net deposition isassociated with the E/D ratio less than one, thus forming the thirdsub-region 302C. Additionally, at a second time, when the secondsub-region 302B is being formed, the E/D ratio is set to a secondnumber, such as a number greater than one. In some embodiments, when theE/D ratio is greater than one, a deposition rate of the E/D ratio isless than an etching rate for the E/D ratio. Accordingly, a net etchingis associated with the E/D ratio greater than one, thus etching back(not shown) at least a portion of the second sub-region 302B.Additionally, at a third time, when the first sub-region 302A is beingformed, the E/D ratio is set to be less than one, such as the firstnumber, for example. Accordingly, the first sub-region 302A is formed.In some embodiments, the third sub-region 302C is below at least some ofthe second sub-region 302B and the second sub-region 302B is below atleast some of the first sub-region 302A. For example, the firstsub-region 302A is at a surface of region 102. In some embodiments, afirst material is applied to at least one of at least some of the firstregion 102, the first sub-region 302A, the second sub-region 302B, orthe third sub-region 302C during formation. For example, applying thefirst material to the respective regions or sub-regions enablescompressive stress to be induced such that at least one of electronmobility or hole mobility is enhanced for at least one of the respectiveregion or sub-regions, for example. In some embodiments, Germanium (Ge)is applied to at least one of at least some of the region 102, the firstsub-region 302A, the second sub-region 302B, or the third sub-region302C. Additionally, in some embodiments, different concentrations of thefirst material are applied at different times, such as based on the E/Dratio. For example, when the E/D ratio is less than one, a firstconcentration of the first material is applied. In another example, whenthe E/D ratio is greater than one, a second concentration of the firstmaterial is applied. In some embodiments, the first concentration of thefirst material is applied to at least one of at least some of the region102 or the third sub-region 302C at a first time, such as when the E/Dratio is less than one. In some embodiments, the second concentration ofthe first material is applied to at least one of at least some of theregion 102 or the second sub-region 302B at a second time, such as whenthe E/D ratio is greater than one. In some embodiments, the firstconcentration of the first material is applied to at least one of atleast some of the region 102 or the first sub-region 302A at a thirdtime, such as when the E/D ratio is less than one. In some embodiments,the first sub-region is associated with the first concentration of thefirst material, the second sub-region is associated with the secondconcentration of the first material, and the third sub-region isassociated with the first concentration of the first material.Accordingly, 310 is a graph of depth versus doping concentration forregion 102. For example, 310A corresponds to the first sub-region 302A,310B corresponds to the second sub-region 302B, and 310C corresponds tothe third sub-region 302C. It will be appreciated that at least some of310A and at least some of 310C are associated with a same dopingconcentration, such as a first doping concentration, while 310B isassociated with a different doping concentration, such as a seconddoping concentration, at least because 310B is associated with 302B anda different E/D ratio than 310A, 310C, and 302A, 302C, for example. Inthis way, the concentration of the first material is controlled based onthe E/D ratio. In some embodiments, a Ge concentration associated withat least one of 302A, 302B, or 302C is at least about twenty percent toat least about fifty percent, for example. However, it will beappreciated that in other embodiments, the Ge concentration is at leastone of less than twenty percent or greater than fifty percent.

FIG. 4 is a flow diagram of an example method 400 for controlling asurface profile for a region of a semiconductor, according to someembodiments. For example, the method 400 comprises setting an etching todeposition (E/D) ratio to a first number less than one during formationof a region at 402. In some embodiments, the method 400 comprisessetting the E/D ratio to the first number at a first time. Additionally,the method 400 comprises setting the E/D ratio to the second number at asecond time, the second time after the first time. In some embodiments,the method 400 comprises returning the E/D ratio to the first number ata third time, the third time after the second time. At 404, the method400 comprises setting the E/D ratio to a second number greater than one,thus controlling a surface profile for the region. According to someaspects, the method 400 comprises applying a first concentration of afirst material to the region at the first time and applying a secondconcentration of the first material to the region at the second time. Insome embodiments, the method 400 comprises applying the firstconcentration of the first material at a third time, the third timeafter the second time. For example, in some embodiments, the firstmaterial is Germanium (Ge). In some embodiments, the method 400comprises determining the second concentration based on a change in theE/D ratio from the first number to the second number. For example, thesecond concentration is determined based on a rate of change from thefirst number to the second number. In some embodiments, at least one ofthe second time or setting the E/D ratio to the second number is basedon a thickness of the region. In some embodiments, forming the region isbased on at least one of epitaxial growth or chemical vapor deposition(CVD).

FIG. 5 is a flow diagram of an example method 500 for controlling asurface profile for a region of a semiconductor, according to someembodiments. In some embodiments, the method 500 comprises forming theregion based on at least one of epitaxial growth or chemical vapordeposition (CVD). At 502, the method 500 comprises setting an etching todeposition (E/D) ratio to a first number less than one at a first timeduring formation of a region. At 504, the method 500 comprises applyinga first concentration of a first material to the region at the firsttime. At 506, the method 500 comprises setting the E/D ratio to a secondnumber greater than one at a second time, the second time after thefirst time. For example, the E/D ratio is set to the second number basedon a thickness of the region. At 508, the method 500 comprises applyinga second concentration of the first material to the region at the secondtime, thus controlling a surface profile for the region. For example,the second concentration is determined based on at least one of thefirst number, the second number, or a difference between the secondnumber and the first number. In some embodiments, the method 500comprises returning the E/D ratio to the first number at a third time,the third time after the second time. Additionally, the method 500comprises applying the first concentration of the first material to theregion at a third time, the third time after the second time. In someembodiments, the method 500 comprises at least one of applying a firstconcentration of Germanium (Ge) to the region at the first time,applying a second concentration of Germanium (Ge) to the region at thesecond time, or applying a first concentration of Germanium (Ge) to theregion at a third time.

According to some aspects, a method for controlling a surface profilefor a region of a semiconductor is provided, comprising setting anetching to deposition (E/D) ratio to a first number less than one duringformation of a region. In some embodiments, the method comprises settingthe E/D ratio to a second number greater than one, thus controlling asurface profile for the region.

According to some aspects, a method for controlling a surface profilefor a region of a semiconductor is provided, comprising setting anetching to deposition (E/D) ratio to a first number less than one at afirst time during formation of a region. In some embodiments, the methodcomprises applying a first concentration of a first material to theregion at the first time. In some embodiments, the method comprisessetting the E/D ratio to a second number greater than one at a secondtime, the second time after the first time. In some embodiments, themethod comprises applying a second concentration of the first materialto the region at the second time, thus controlling a surface profile forthe region.

According to some aspects, region of a semiconductor associated with acontrolled surface profile is provided, comprising a first sub-region ata surface of a region, the first sub-region associated with a firstconcentration of a first material. In some embodiments, the regioncomprises a second sub-region below at least some of the firstsub-region. Additionally, the second sub-region is associated with asecond concentration of the first material and the second concentrationis different than the first concentration. In some embodiments, theregion comprises a third sub-region below at least some of the secondsub-region. Additionally, the third sub-region is associated with thefirst concentration of the first material.

Although the subject matter has been described in language specific tostructural features or methodological acts, it is to be understood thatthe subject matter of the appended claims is not necessarily limited tothe specific features or acts described above. Rather, the specificfeatures and acts described above are disclosed as example forms ofimplementing the claims.

Various operations of embodiments are provided herein. The order inwhich some or all of the operations are described should not beconstrued as to imply that these operations are necessarily orderdependent. Alternative ordering will be appreciated based on thisdescription. Further, it will be understood that not all operations arenecessarily present in each embodiment provided herein.

It will be appreciated that layers, features, regions, elements, such asthe region, surface of the region, first sub-region, second sub-region,third sub-region, etc. depicted herein are illustrated with particulardimensions relative to one another, such as structural dimensions ororientations, for example, for purposes of simplicity and ease ofunderstanding and that actual dimensions of the same differsubstantially from that illustrated herein, in some embodiments.Additionally, a variety of techniques exist for forming the layers,features, regions, elements, etc. mentioned herein, such as implantingtechniques, etching techniques, doping techniques, spin-on techniques,sputtering techniques such as magnetron or ion beam sputtering, growthtechniques, such as thermal growth or deposition techniques such aschemical vapor deposition (CVD), for example.

Moreover, “exemplary” is used herein to mean serving as an example,instance, illustration, etc., and not necessarily as advantageous. Asused in this application, “or” is intended to mean an inclusive “or”rather than an exclusive “or”. In addition, “a” and “an” as used in thisapplication are generally construed to mean “one or more” unlessspecified otherwise or clear from context to be directed to a singularform. Also, at least one of A and B and/or the like generally means A orB or both A and B. Furthermore, to the extent that “includes”, “having”,“has”, “with”, or variants thereof are used in either the detaileddescription or the claims, such terms are intended to be inclusive in amanner similar to the term “comprising”.

Also, although the disclosure has been shown and described with respectto one or more implementations, equivalent alterations and modificationswill occur based on a reading and understanding of this specificationand the annexed drawings. The disclosure includes all such modificationsand alterations and is limited only by the scope of the followingclaims.

What is claimed is:
 1. A region of a semiconductor associated with acontrolled surface profile, comprising: a first sub-region at a surfaceof a region, the first sub-region associated with a first concentrationof a first material; a second sub-region below the first sub-region, thesecond sub-region associated with a second concentration of the firstmaterial, the second concentration different than the firstconcentration; and a third sub-region below the second sub-region, thethird sub-region associated with the first concentration of the firstmaterial.
 2. The region of claim 1, wherein the first material isGermanium.
 3. The region of claim 1, wherein the first sub-region is incontact with the second sub-region.
 4. The region of claim 1, whereinthe second sub-region is in contact with the third sub-region.
 5. Theregion of claim 1, wherein: the first sub-region is in contact with thesecond sub-region; and the second sub-region is in contact with thethird sub-region.
 6. The region of claim 1, wherein a surface of thefirst sub-region has a grain size of at least forty nanometers.
 7. Theregion of claim 1, wherein the second concentration is less than thefirst concentration.
 8. The region of claim 1, wherein the firstconcentration is between about twenty percent and about fifty percent.9. The region of claim 8, wherein the first material is Germanium. 10.The region of claim 1, wherein the second concentration is selected as afunction of a change in an etching to deposition (E/D) ratio betweenformation of the first sub-region and formation of the secondsub-region.
 11. The region of claim 1, wherein the second concentrationis selected as a function of a change in an etching to deposition (E/D)ratio between formation of the second sub-region and formation of thethird sub-region.
 12. A region of a semiconductor associated with acontrolled surface profile, comprising: a first sub-region associatedwith a first concentration of Germanium; a second sub-region below thefirst sub-region and in contact with the first sub-region, the secondsub-region associated with a second concentration of Germanium, thesecond concentration different than the first concentration; and a thirdsub-region below the second sub-region and in contact with the secondsub-region, the third sub-region associated with the first concentrationof the Germanium.
 13. The region of claim 12, wherein a surface of thefirst sub-region has a grain size of at least forty nanometers.
 14. Theregion of claim 12, wherein the second concentration is less than thefirst concentration.
 15. The region of claim 12, wherein the secondconcentration is selected as a function of a change in an etching todeposition (E/D) ratio between formation of the first sub-region andformation of the second sub-region.
 16. The region of claim 12, whereinthe second concentration is selected as a function of a change in anetching to deposition (E/D) ratio between formation of the secondsub-region and formation of the third sub-region.
 17. The region ofclaim 12, wherein the first concentration is between about twentypercent and about fifty percent.
 18. A region of a semiconductorassociated with a controlled surface profile, comprising: a firstsub-region associated with a first concentration of a first material, atop surface of the first sub-region having a grain size of at leastforty nanometers; a second sub-region below the first sub-region, thesecond sub-region associated with a second concentration of the firstmaterial, the second concentration different than the firstconcentration; and a third sub-region below the second sub-region, thethird sub-region associated with the first concentration of the firstmaterial.
 19. The region of claim 18, wherein the first material isGermanium.
 20. The region of claim 18, wherein the second concentrationis selected as a function of a change in an etching to deposition (E/D)ratio between formation of the third sub-region and formation of thesecond sub-region.